Pneumatic tool



Auge Q n ,SMITH :ET AL PNEtiran-1''c Toom VFiled -Ju'rxegy Je.,Y img: 2 Sheena-sheer 1 Aug. 26. 1924.l 1,506,141

' W. A. SMITH ET AL PNEUMATIC TOOL Pneu ne es.v 19m sheemsheer 2 Patented Aug. 26, 1924.4

UNITED .STATES PATENT OFFICE WILLIAM A. vSMITH AN D ACLAREN CE H. DOCKHM, 10F DETROIT, MICHIGAN, ASSIGNO'RS 'T0 CHICAGO EPNEUMATIC TOOL COMPANY, OF NEW YORK, N. Y., .A CORPORATION 0F NEW JERSEY.

PNEUMATIC TOOL.

To .all ,whom it may concern.:

YBe it known that we, VILLMM A. SMITH and .CLARENCE H. DOCKHAM, both citizens of the United States of America, residing at Detroit, in the county of lVayne and State vOf lVIichigan, have invented certain new .and useful Improvements in Pneumatic Tools, of which the following is a ,specification, vreference being had therein to the accompanying drawings.

The invention relates to pneumatic tools and has more particular reference to the construction of controlling valve therefor, as hereinafter set forth.

In the drawings:

Figure l is a longitudinal section through the tool in .the .axial plane Vof the valve;

Figure 2 is a similar View showing the valve shifted to `.another position;

Figure 3 is a cross-section on line 3 3 of Figure l.;

Figure 4 is a cross-section on line L -4 of Figure l;

Figure 5 is a cross-section on line 5-5 of Figure 1,; y"Figures `6 and 7 .are longitudinal sections showing the piston at opposite ends of the cylinder .and taken respectively on lines 6--6 .and 7 7 of VFigures 2 and l.

The .cylinder .A of the tool is provided .with a. central annular :groove B forming an exhaust channel opening through the port C to the atmosphere. `D is the piston within .the cylinder which is adapted to over-run the exhaust port C, and E is the piston shank engaging the cylinder guide F and impinging against the end of the tool Gr held therein. Y

The valve casing is formed by a boss H projecting from one ,side of the cylinder and having a cylindrical bore extending transversely therethrough. The central portion of this bore is connected to the fluid supply passage I and on one side .of this passage is the passage J leading to the outer .end of the cylinder .and coinmruiieating therewith thro-ugh `the port K. On the opposite side `of lthe passage I 'is .a Ltransverse port or passage L extending .downward into the Acylinder at the .opposite end thereof from the port K. The cylindrical bo-re through the valve casing has va port-ion M of large `diameter .extending from the .central passage .I to one ,end of the bore and a portion N of smaller diameter ex- 1921. Serial No. 475,536.

tending from said central passage to the opposite end of the bore. O is a sleeve valve having a portion P for fitting the large diameter portion M vof the bore and a portion 'Q for fitti-ng the small diameter end of said bore. These two portions of the valve are connected by a central portion It of smaller diameter and the whole valve is slidably mounted on a bolt S, which serves 1to clamp in place the caps T and U for closing the opposite ends of the bore. The cap U has a portion U1 extending within a cylindrical recess in the small diameter portion Q lof the valve and surrounding this portion Ul the cap is provided with an annular series of exhaust ports U2 communicating with the external atmosphere. The cap T has a portion T1L projecting into the portion P of the valve, but not closely fitting the same, so as to form an annular chamber V. This chamber in one position of the valve is in open communi-cation with a port or passage 7 which extends t-o the cylinder A in a position to be sealed by the piston when at the end of its forward stroke. The valve cylinder is provided with annular grooves H1, H2, H3 and H4, which are respectively connected to the passa-ges J, I and L and form ports for cooperating with the heads of the valve.

In operation, the passage I being connected to a source of fluid under pressure, such as compressed air, and the valve being in the position ,shown in Fig. 2 with the piston in the position indicated in dotted lines, the compressed air .or other iuid will pass through the channel H2 and the central portion ofthe valve chamber into the channel H1., passage J and the port K to the cylinder 4and will kdrive the piston l) forward. At the same time a portion of the compressed air will pass through a restricted port X into the annular chamber V within the portion P .ofthe valve, but as this chamber is in communication through the passage `W with the forward end of the cylinder, which latter is .in free .communication with the exhaust channel B, the pressure will not be greatly in excess of atmosphere. Therefore, the valve will be held in the position shown by the `differential pressure on the large and small diameter portions P and Q. As soon, however, as vthe piston D over-rides the exhaust channel vB and seals the passage W, pressure will 'be built up within the channel V by the leakage through the restricted port X. This pressure, acting upon the large area end of the valve, will cause the shifting of the valve into the position shown in Fig. l, where communication between the passages I and J is cut olf and communication is established between the passage I and the passage L. The compressed air will therefore flow through the passage L into the cylinder and will exert a pressure upon the piston for returning the same, the pressure on the opposite side being reduced to atmosphere through communication with the exhaust port C. After the piston has over-run the exhaust port, the pressure on the large area end of the valve will be exhausted through the channel 1V and exhaust port C, which will again cause the shifting of the valve, cutting off communication betweenthe passages I and L and re-establishing communication between the passages I and J. The shifting of the portion Q of the valve will also uncover the channel I-It, which through the port H5 is in communication with the pas'- sage L and this opens connection between said passage L and the ports U2 opening to the atmosphere. Thus when the piston has again driven forward and over-rides the main exhaust port B, theairreinaining ,in the cylinder in front ofthe piston will be forced out through the passage L, port H5, channel I-It and ports U2. i

The construction as above described is exceedingly simple and can be manufactured at low cost, while the forming of the valve cylinder by a transverse bore and the supporting of the spool'valve upon the bolt, which secures the end caps for the valve casing, forms a construction which is very easily assembled. y

Vhat we claim as our invention is:

l. In a pneumatic tool, the combination with a piston and a cylinder having a main exhaust vport over-run by said piston, of a valve construction comprising a cylindrical 'casing having portions of different diameters with a pressure supply port intermediate the same, a valve having heads fitting the portions of different diameters and sub- Y jected to differential pressure of the fluid supply, a leak passage from the fluid supply to the end of the casing of Ilarger diameter and a passage from said end of the casing to the cylinder in a position to be sealed by the piston while atV one end of its stroke and to be in communication with the main exhaust port when said piston is at the opposite end of its stroke, whereby pressure on the large area end of the valve lis alternately built up and exhausted.

2. In a pneumatic tool, the combination with a piston and a cylinder having a main exhaust port over-run by said piston, of a valveV construction comprising a cylindrical casing having opposite end portions thereof of different diameters and having a pressure supply port therebetween, a valve provided with heads fitting the Vportions of different diameters and subjected to the differential pressure of the fluid supply, a leak passage from the fluid supply to the large area end of the casing, an exhaust port for the small area end of the casing and a passage from the large area end to the cylinder located to Y be sealed by the piston when at one end of its stroke, and to be placed in communica# tion with the main exhaust port when said piston is at the opposite end of its stroke, whereby said valve is shifted by the alternate building up and exhausting of pressure, and passages controlled by said valve leading to the opposite ends of said cylinder alternately lplaced in communication with said supply port and the main exhaust port'.

3. In a pneumatic tool, the combination with a piston and a cylinder having a main exhaust port over-run by said piston, of a larger diameter, an exhaust port for theendk of the casing of smaller diameter in .communication with one of the cylinder leading passages when said valve is in one position, and a passage from the large area end of said casing to said cylinder sealed by said piston when at one end of its stroke and placed in communication with the main exhaust passage when the pistonrris at the other end of its stroke. y

4, In a pneumatictool, thecombination with a piston and a cylinder having a main exhaust port over-run by said piston, ofaa valve construction comprising a cylindrical casing having opposite end portions thereof of different diameters and provided with ports and connecting passages for leading to the opposite ends of said cylinder, anda central fluid-'supply port, a valve having head portions litting said'end portions of the cylinder and subjected to the'dilferential pressure of the fluid supply, a passage from the large diameter end of said casing lead# ing to-one end of saidvv cylinder in a posi'-Y tion to be sealed by said piston while at one end of its stroke and placed in communication with the main exhaust port when said piston is at the opposite endof the stroke, and a bleedportthrough the'large end of said valve, whereby" pressure is alternately built up and exhausted at Vthe Y 5. In a pneumatic tool, the combination with a piston and a cylinder having a main exhaust port over-run by said piston, of a valve construction comprising a cylindrical casing having opposite end portions thereof of different diameters and provided with ports and connecting passages for leading to the opposite end of said cylinder, a spool valve having portions fitting the portions of said casing which are of diferent diameters and controlling said ports and passages, caps for closing the opposite ends of said valve casing, a bolt for clamping said caps passing axially through said casing and valve and forming a guide for the latter, a passage from the large diameter end of said casing leading` to one end of said cylinder in a position to be sealed by the piston while at that end, and a bleed port establishing restricted communication between said large diameter end of the casing and the fluid pressure passage, whereby pressure is alternately built up and exhausted at said large diameter end to effect the shifting of the valve.

6. In a pneumatic tool, the combination of a piston and a cylinder therefor having a main exhaust port over-run by the piston, of a valve construction comprising a casing having a transverse bore with lportions thereof of different diameters, said bore having annular channels communicats ing with a source of fluid under pressure, and channels leading to the opposite ends of said cylinder, a spool valve within said valve chamber having portions iitting the portions of different diameter thereof, caps for closing the o-pposite ends of said casing, a bolt for clamping said caps, passing axially through said casing and spool valve, a passage leading from the large diameter end of said valve casing to one end of said cylinder in a position to be sealed by the piston while at said end and to be in communication with the main exhaust port when said piston has over-ridden the same, and

a bleed port in said Valve establishing restricted communication between the source of fluid under pressure and the large diameter end of the valve casing, whereby the pressure acting on the large area end of said valve is alternately built up and exhausted by the reciprocation of said piston and the sealing and unsealing of the passage thereby.

7. In a pneumatic tool, the combination with a piston, of a cylinder having a main exhaust port over-ridden by the piston and a boss projecting from one side of said cylinder transversely bored to form a valve casing having port-ions of different diameters, said casing having annular channels therein communicating with a source of Huid under pressure and with passages leading to the opposite ends of said cylin er, a spool valve itting the portions of said casing of dilerent diameter and controlling the ports and passages thereof, caps for closing the opposite ends of said casing, the cap for the small diameter end having an inwardly projecting portion fitting a recess in said valve and provided with exhaust ports outside of said portion, a bolt for clamping said caps passing axially through said cas ing and valve, a passage connecting the large diameter end of said casing with said cylinder at one end thereof in a position to be sealed by the piston while at said end, a bleed port through said valve establishing restricted communication between the source of luid under pressure and the large diameter end of said casing, whereby pressure operating on the large area end of the piston is alternately built up and exhausted, and a passage for connecting one end of said cylinder with the auxiliary exhaust through said cap when said valve is in one position of adjustment.

In testimony whereof we aifix our signatures.

WILLIAM A. SMITH. CLARENCE H. DOCKHAM. 

